Many types of viruses gain access to the human body via the respiratory tract, primarily in the form of aerosolized droplets or saliva. This is the most frequent means of viral entry into the host. Successful infection occurs despite nor mal host protective mechanisms, including the mucus covering most surfaces, ciliary action, collections of lymphoid cells, alveolar macrophages, and secretory IgA. Many infections remain localized in the respiratory tract, although some viruses produce their characteristic disease symptoms after systemic spread (eg, chickenpox, measles, and rubella; see Table 1 and Figure 1).

Table1. Common Routes of Viral Infection in Humans

Fig1. Mechanisms of spread of virus through the body in human viral infections. + indicates possible sites of viral replication; large arrows indicate sites of shedding of virus, with illustrative examples of diseases in which that route of excretion is important. Transfer from blood is by transfusion with hepatitis B and by mosquito bite in certain arboviral infections. SSPE, subacute sclerosing panencephalitis. (Modified from Mims CA, White DO: Viral Pathogenesis and Immunology. Copyright © 1984 by Blackwell Science Ltd. With permission from Wiley.)

Respiratory infections impose a heavy disease burden worldwide. Respiratory infections are the most common cause of mortality for children younger than 5 years, with diarrheal disease the second leading cause. Disease symptoms exhibited by the host depend on whether the infection is concentrated in the upper or lower respiratory tract (Table 2). The severity of respiratory infection can range from inapparent to overwhelming. Although definitive diagnosis requires isolation of the virus, identification of viral gene sequences, or demonstration of a rise in antibody titer, the specific viral disease can frequently be deduced by considering the major symptoms, the patient’s age, the time of year, and any pattern of illness in the community.

Table2. Viral Infections of the Respiratory Tract

اخر الاخبار

اخبار العتبة العباسية المقدسة

تقديم المحاضرة السابعة من محفل نهج البلاغة الأسبوعي في ذي قار

مركز السيد جعفر الحلي يواصل تقديم خدماته الصحية للزائرين

العتبة العباسية المقدسة تحيي ذكرى هدم قبور أئمّة البقيع (عليهم السلام) في الصحن الشريف

تقديم المحاضرة السادسة من محفل نهج البلاغة الأسبوعي في بغداد

المزيد

الآخبار الصحية

اكتشاف هام قد يمهّد لعلاج جديد للسمنة

تغييرات بسيطة في نمط الحياة تقلل خطر أمراض القلب بنسبة كبيرة

ليس اللب فقط!.. قشرة وبذور المانغو تخفي فوائد صحية مذهلة

زيادة استهلاك الكالسيوم ومنتجات الألبان يحمينا من مشكلات صحية خطيرة

المزيد

الآخبار التكنلوجية

العلماء الروس يكتشفون طريقة تحسن فرص نجاح زراعة الأسنان

لحظة زمنية خاطفة في الدماغ تتحكم في التعلم والحركة

القمر لم يعد مجرد محطة.. خطوة جديدة تغيّر مستقبل البشرية

العلماء يكتشفون "نوعا جديد تماما" من الكواكب

المزيد

مواضيع ذات صلة

HIV Infections in Humans: Laboratory Diagnosis

HIV Infections in Humans :Clinical Findings

HIV Infections in Humans : Pathogenesis and Pathology

Animal Lentivirus Systems

Classification of Lentiviruses

Viral DNA Is Integrated into the Host-Cell Genome in Some Nonlytic Viral Growth Cycles

Lytic Viral Growth Cycles Lead to Death of Host Cells

Viral Capsids Are Regular Arrays of One or a Few Types of Protein

Structure and Composition of Lentiviruses

HERPESVIRUSES

POLYOMAVIRUSES

Human T-Lymphotropic Viruses